Phonographic apparatus



Jill??? 11%? J. J. HOEHN 2,247,659

PHONOGRAPHIC APPARATUS Filed May 7, 1940 2 Sheets-Sheet I 3nventor J. J.HOEHN PHONOGRAPHIC APPARATUS 2 Sheets-Sheet 2 Filed May 7, 19 .0

EG- J.

Patented July 1, 1941 2,247,659 PHONOGRAPHIC APPARATUS John J. Hoehn,Indianapolis, Ind., assignor to Radio Corporation of America, acorporation of Delaware Application May 7, 1940, Serial No. 333,705

6 Claims.

This invention relates to phonographic apparatus, and more particularlyto apparatus for recording sound upon a record disc for immediatereproduction from the record.

It is well known that, in apparatus of this sort, the load imposed uponthe record blank by the cutter when a sound groove is being recorded ismuch greater than the load imposed upon the reproducing needle when thefinished record is being reproduced. Under ordinary circumstances, theadditional load imposed by the recording stylus is usually suflicient tocause slippage of the record blank upon the turntable which supports it,and as a consequence, there results distortion in the recording. Toobviate this, it has been proposed to provide the turntable with one ormore eccentric driving pins which are adapted to be received bycorresponding openings in the record blank to provide a positive drivefor the record and to prevent slipping thereof relative to theturntable. Obviously, this limits the use of such a turntable only torecords which are provided with openings corresponding to the eccentricdriving pins on the turntable. It is usually desirable, however, to alsoreproduce standard records by means of the same apparatus, theconventional standard records having no eccentric openings for receivingthe aforementioned eccentric driving pins.

The primary object of my present invention is to provide an improvedphonographic apparatus wherein the aforementioned difficulty is avoided.

More particularly, it is an object of my present invention to provideimproved phonographic apparatus by means of which it will be possible torecord upon and reproduce from records of both the standard type and thetype having eccentric openings therein as aforementioned.

Another object of my present invention is to provide an improvedphonograph turntable which is adapted to receive both standard andspecial records as aforementioned and which can be arranged for thispurpose with great facility.

Still another object of my present invention is to provide an improvedturntable as aforesaid which is simple in construction andinexpensive tomanufacture.

In accordance with my invention, I provide in the turntable hub a pairof eccentric bores which extend longitudinally therethrough. In one ofsaid bores, I provide a driving pin which is normally biased by asuitable spring to an elevated position such that it protrudes above therecordsupporting surface of the turntable, the said driving pin beingdepressible under the weight of a standard record against the action ofthe spring into a lowered position where the top of the driving pin issubstantially flush with the record-supporting surface of the turntable.When so lowered, the lower end of the driving pin projects through thebottom of the turntable and exposes an annular groove therein into whicha leaf spring, secured to the bottom of the turntable hub, is adapted toslide and which acts as a detent to releasably lock the driving pin inlowered position. In the second of the aforementioned bores is a plungerthe lower end of which is formed with a cone constituting a cam elementwhich rests against the aforementioned leaf spring, and the action ofsaid leaf spring on the cone normally holds the plunger in elevatedposition such that the tip of the plunger is slightly below therecord-supporting surface of the turntable. When the plunger isdepressed, the cone or cam element thereon bears against the leaf springand forces it out of the annular groove in the driving pin, whereby thecoil spring associated with the driving pin becomes free to raise thedriving pin into its elevated position in readiness to be received inthe eccentric opening of a special record.

The novel features that I consider characteristic of my invention areset forth with particularity in the appended claims. The inventionitself, however, both as to its organization and method of operation, aswell as additional objects and advantages thereof, will best beunderstood from the following description of one embodiment thereof,when read in conjunction with the accompanying drawings wherein Figure 1is a fragmentary top plan view of a phonograph turntable embodying oneform of wherein similar reference numerals indicate cor-' respondingparts throughout, I have shown a turntable l provided with the usual hub3 having a central bore through which extends a motor shaft terminatingin the conventional recordcentering spindle 5. The hub 3 is alsoprovided with a pair of bores l and 9, and within the bore l is mounted,for longitudinal movement therein, a driving pin ll formed with anannular groove l3. and having secured thereto a pair of fixed collars orwashers l5 and IT. A coil spring l9, surrounding the driving pin II andinterposed between the collar [5 and a shoulder 2| formed in the bore 1,tends constantly to raise the driving pin it to the elevated positionshown in Fig. 2, wherein the driving pin extends above therecord-supporting surface of the turntable to en-' gage the eccentricopening 23 of a record blank R of the special type. It is obvious,therefore, that the driving pin Ii will provide a positive drive for therecord R when in raised position.

If desired, a mat 25 of rubber, felt, or the like,

may be provided as a facing orcovering for the turntable to provide goodfrictional contact between the turntable l and the record blank R when astandard record is used on the turntable I.

Mounted for longitudinal movement in the bore 9 is a rod or plunger 21formed with a cone 29 on its lower end, the cone 29 being receivedbetween and resting upon the arms 3la of a U- shaped or hairpin-shapedleaf spring 3| secured to the bottom of the hub 3, as by means of ascrew 33. The spring 3| is so formed that the arms am thereof constantlytend to move toward each other in the directions of the arrows A (Fig.4) and, acting on the cone 29, the spring 3| constantly tends to holdthe plunger 21 in elevated position wherein the upper tip of theplunger-21 is slightly lower than the record-supporting sur-. face ofthe turntable. The spring arms 3|a also straddle the lower end of thedriving pin II and act as a stop against which the collar I1 bears inthe elevated position of the driving pin l I.

When a record of the special type heretofore mentioned is to be used onmy improved turntable, the driving pin is permitted to remain in theposition shown in Fig. 2' and the protruding upper end of the drivingpin II is received in the eccentric opening 23 of the special record. Ifit is desired to play a standard record,'al1 that is necessary is tothread the record on the centering spindle 5, the record thereuponresting on the upper end of the driving pin II and causing it to bedepressed into its lower position, as shown in Fig. 3, the weight of therecord being sumcient to overcome the force of the spring l9. When thisis done, the side arms 3la of the detent sprin 3|, moving in thedirections of the arrows A (Fig. 4), automatically slip into the grooveI3 and releasably lock the driving pin H in its lowered position, asshown in Fig. 3. If, thereafter, it is desired to either record upon orreproduce from a special record as aforementioned, the plunger21 isdepressed, whereupon the cam element or cone 29 forces the arms 3la ofthe spring 3| apart in the directions of the arrows B and into thedotted line position of Fig. 4 to disengage the arms 3la from theannular groove l3, whereupon the spring 19 immediately raises thedriving pin H to its elevated position again.

From the foregoing description, it will be apparent to those skilled inthe art that I have provided a novel and improved turntable which isadapted to accommodate records of both the standard type and the specialtype. Although I have shown and described but one embodiment of myinvention, it will be apparent to those skilled in the art that manyother modifications are possible. For example, instead of using merelyone eccentric driving pin, I may provide several such pins andassociated mechanisms around the centering spindle 5 and either on thesame radius or at difierent radii. Many other changes will, no doubt,readily suggest themselves to those skilled in the art. I, therefore,desire that my invention shall not be limited except insofar as is madenecessary by the prior art and by the spirit of the appended claims.

I claim as my invention:

1. In phonographic apparatus, a turntable for supporting a record inoperative position, said turntable including a driving pin arrangedeccentrically with respect to the turntable center and adapted to bereceived in a corresponding eccentric opening in the record to providedriving engagement therewith, said driving pin being movably mounted onsaid turntable for movement between an elevated position wherein saiddriving pin extends above the record-supporting surface of saidturntable and a lowered position wherein the tip of said driving pin issubstantially flush with said surface, yieldable means constantly urgingsaid driving pin to said elevated position, said means being adapted toyield under the weight of a-record on said turntable whereby to effectlowering of said driving pin-to said lowered position when a record isplaced thereon which has no corresponding eccentric opening to receivesaid pin, and means for releasably locking said driving pin in saidlowered position. v

2. In phonographic apparatus, a turntable for supporting a record inoperative position, said turntable including a driving pin arrangedeccentrically with respect to the turntable center and adapted to bereceivedin a corresponding eccentric opening in the record to providedriving engagement therewith, said driving pin being movably mounted onsaid turntable for movement between an elevated position wherein saiddriving pin extends above the record-supporting surface of saidturntable and a lowered positionwherein the tip of said driving pin'issubstantially flush with said surface, yieldable means constantlyurgingsaid driving pin to said elevated position, said means being adapted toyield under the weight of a record on said turntable whereby to effectlowering of said driving pin to said lowered position when a record isplaced thereon which has no corresponding eccentric opening to receivesaid pin, means for releasably locking said driving pin in said loweredposition, and means for releasing said locking means to render saidyieldable means free to elevate said driving pin to said elevatedposition.

3. The invention set forth in claim 1 characterized in that saidturntable is provided with a bore eccentric to the turntable center,characterterized in that said turntable is provided with a boreeccentric to the turntable center, characterized further in that saiddriving pin is mounted in said bore for longitudinal movement therein,characterized further in that said driving pin is provided with a grooveat a portion therein which extends below said turntable ,whensaid pin isdepressed into said lowered position, and characterized still further inthat said locking means comprises a leaf spring secured to the bottom ofsaid turntable and biased toward said pin whereby said leaf spring isadapted to slip into said groove when aid pin is lowered to therebyreleasably lock said pin in said lowered position.

5. The invention set forth in claim 2 characterized in that said lockingmeans comprises a movably mounted detent movable into locking engagementwith said driving pin, and characterized further in that said means forreleasing said detent includes a cam arranged to engage said detent toforce it out of locking relation with said driving pin.

6. The invention set forth in claim 2 characterized in that saidturntable is provided with a pair of bores each eccentric to theturntable center, characterized further in that said driving pin ismounted in one of said bores for longitudinal movement therein,characterized further in that said driving pin is provided with a grooveat a point therein which extends below said turntable when said pin isdepressed into said lowered position, characterized further in that saidlocking means comprises a leaf spring secured to the bottom of saidturntable and biased toward said pin whereby said leaf spring is adaptedto slip into said groove when said pin is lowered to thereby releasablylock said pin in said lowered position, and characterized still furtherin that said means for releasing said locking means comprises a plungermounted for longitudinal movement in the second of said bores, saidplunger including a cam element normally resting on said leaf spring andsaid leaf spring normally holding said plunger in elevated position onsaid turntable by engagement with said cam element, and

said cam element being adapted to force said leaf spring out of saiddriivng pin groove to release said driving pin and permit said yieldablemeans to raise said driving pin to said elevated position.

JOHN J. HOEHN.

